Next...

[itsid]

7.8 mm² ? I have used cables bigger than that...

anyways the ratio will remain,
but 1/3 shouldn't be too much of a problem regarding accumulation of cuttings.
In fact I believe you need some decrease to increase the flow inside the collector.

I think the main problem is about fluid dynamics, which I know very very little about to be honest.

Maybe you want to try something like that:
clean everything up, start the mower and move no more than a few feet, kill the engine and see if you already collected clippings in the funnel.

If I'm correct you'll notice clippings collect on the inside of the curve.
about there:


I think a simple divider like this:

could prevent that by increasing the flow at that area.
50/50 at both ends. *shrugs*

Again, fluid dynamics isn't exactly my bright spot to talk about,
so I might be completely wrong about your problem, but I guess that's what I'd try first before I start all over again

'sid

 

[OzFab]

7.8 mm² ? I have used cables bigger than that...

That's a comma, indicating thousands, not a decimal point...

I like your thinking but, the simple fact is, the blockage occurs where the funnel meets the pipe; I'm almost certain it's because the funnel is too restricted.

Having said that, I will check out your suggestion

 

[itsid]

That's a comma, indicating thousands, not a decimal point...

sorry.. we do it exactly the other way around in germany, I got confused (again)
1,000,000.5 (en)
1.000.000,5 (de aswell as it)
1 000 000,5 (fr)
1'000'000,5 (ch)

I think I like the swiss format the best.. no chance for confusion and still easy to read

Nevermind,
clogging...

the simple fact is, the blockage occurs where the funnel meets the pipe;

well in that case, I'm afraid it wouldn't help much (if at all)
maybe the shape created a turbulence which sucks the cuttings back down the pipe, but honestly I don't think so
it's too round to do so I'd say.

Two things left:
diameter too small and not enough room for the cuttings to go through.
OR diamter too large and not enough pressure to move the cuttings up the pipe.

I hope you can figure it out

you don't happen to have a leaf vacuum to attach to the upper end, just for some testing, do you?

'sid

 

[Poboy kartman]

I know- smoke testing, like they do in wind tunnels......

Here's watcha do-see. Gitcha some gas or peetrol or whatever it is y'all calls it and pour a leetle bit on the grass and then fire that booger up.......

 

[OzFab]

Two things left:
diameter too small and not enough room for the cuttings to go through.
OR diamter too large and not enough pressure to move the cuttings up the pipe.

As I said, I think the diameter is too small; I'm getting plenty of pressure at the top end of the pipe.

My buddy made an interesting point regarding using a square pipe; he said "it may not produce the necessary vortex to carry the cuttings up the pipe".

you don't happen to have a leaf vacuum to attach to the upper end, just for some testing, do you?

As a matter of fact I do; what are you thinking

 

[itsid]

As a matter of fact I do; what are you thinking

Well at first I thought you could increase the pressure by mounting/holding it to the top of the pipe,
increased airflow basically, but you just said you're getting plenty of pressure already; so that wouldn't help.

That was my idea to judge if the pipe is too small or too large.
Now I think it's indeed just too small.

To increase the momentum of a vortex you would want to force it into a smaller diameter.., that is you could create one at all with that setup.
(A Wolf expert scooter pro uses a square pipe btw )

To be honest I don't think mowers rely on fluid dynamics that much, that any company spend time on designing the collector with much more than flow rates in mind.

Again I know too little about that to provide more than maybe a thought or two,
fluid dynamics was part of my physics class back in scool, for maybe 3 month or so.. (little to learn) and that is a loooong time ago (much to forget)

So back to square one...

Check your local mower dealer for a mower with a similar sized mower deck and see what size of pipe they have at what angle and the basic shape of the collector.
*shrugs*

'sid

 

[OzFab]

So, almost a week later (I've been preoccupied making & remaking rod holders for my buddy's boat), I've made a start on the new chute. I started by tracing the pieces onto new sheet metal & adjusted to allow for a larger tube. I've made some initial bends, now it's time to start working them into shape...

 

[itsid]

I'll keep my fingers crossed

'sid

 

[landuse]

Nice work Tony

 

[OzFab]

3/4 of section 1 done, just need to make the inside wall...

The last 4 pics show the gap between the outside wall & the top & bottom after some careful "manipulation" which included very little cutting, most of the shaping was done by stretching & shrinking...

 

[OzFab]

Getting closer, almost done...

The last week I've been working on the top section of the chute which hasn't exactly been a walk in the park, there was a lot of geometry, stretching, shrinking & tracing involved...

The first thing I had to do was plot thecourse of the lower section onto the cage on the back, then work out the shape & size of the pieces needed. The top & bottom were fairly easy but, the outside wall was a bit of a task...

I first had to make surethe folded edge was at the correct angle then, using a legth of paper, I had to plot the shape of the side onto it, using the bottom as a template...

Of course, the first attempt was wrong because there was a slight lift in the bottom piece which threw the line off. Sorted that out, trimmed the side to suit & we're moving again

Plotting the line of the top was a bit easier, all I had to do was clamp the top & bottom in place & mark the side. Done (eventually), now on to the inside which was rather quick & painless; just a few finishing touches & the top is done.

Now to trim both pieces & make the centre tube...

 

[landuse]

Sweet!

 

[OzFab]

Well, it's been raining here for almost a week so, I sorted the chute, ready to test as soon as the rain stopped, then my brother shows up this morning & mowed all the grass

...& he's the kind of person you can't say "leave it, I'll do it" to because his attitude is "I'm here to do it, I'm doing it" & nothing will stop him...

 

[landuse]

Well, it's been raining here for almost a week so, I sorted the chute, ready to test as soon as the rain stopped, then my brother shows up this morning & mowed all the grass

...& he's the kind of person you can't say "leave it, I'll do it" to because his attitude is "I'm here to do it, I'm doing it" & nothing will stop him...

LOL. You are gonna have to wait another week. The grass here by me is growing so fast at the moment I could cut it twice a week if I had the energy. I assume it is the same with you now

 

[Doc Sprocket]

You've done wonderful job so far. Now- stop mucking about with this silly grass-catcher nonsense, and concentrate on what's important. Lock the differential, get some meaty rubber on there, and mount the winch, already!

 

[OzFab]

Yeah, that's not gonna happen. Remember, I live in the 'burbs so, no need for any of that, this thing is strictly a purpose tool, not a toy (although I do have fun using it )

 

[OzFab]

I found a patch of uncut grass (turns out my brother left me a bit). After 2 runs (around 100 feet), the result of what the inside of the chute looked like can be seen in pic 1. I then removed the bag & tried agian; the result is in pic 2.

I'm now convinced & content with the fact that the bad is causing back pressure (for lack of a better term) preventing the grass from reaching it. The shade cloth material I intend to use on the catcher can breathe a bit more so, I shouldn't have any problem with it...

 

[landuse]

Yeah!! It works well

 

[OzFab]

Ok so, I have a small dilemma; last time I used the mower, it suddenly but, gradually refused to move; engine runs, belts move, foot clutch works ok but, no movement...

After a few visual tests, I came to the conclusion it was something to do with the gearbox; it was only something simple so, knowing that the gearbox was covered in about 30 years worth of crud, I decided to take it apart to clean & repair it.

Now, I usually pay a lot of attention when taking things apart but, this time, obviously, not quite enough because it wasn't until I cleaned the two main gears that I realised they were not quite identical...

Judging by the wear pattern, I think I have it figured out but, I wouldn't mind a second (or third) opinion. The gearbox in question is the small MDT f-n-r unit...

Oh & what was the problem? See the last pic...

 

[landuse]

Looks like your key has shrunk?